Support enum variants documentation

[beeb]

Is your feature request related to a problem? Please describe.

Solidity 0.8.30 added support for documenting enum variants with NatSpec, which can be done inside of the enum definition (above each value).

Describe the solution you'd like

Have lintspec correctly parse those and validate against them.

Examples:

/// @notice Test enum
enum Test {
    /// @param something
    Foo,
    /// @notice description
    Bar,
    /// @return the baz
    Baz
}

Describe alternatives you've considered

Additional context

argotorg/solidity#15956

To be determined whether adding a @notice or @dev above an enum value is considered to be valid documentation as a replacement for @param on the enum itself. Same question for @return or @param which are theoretically allowed on an enum value.